It is currently 18 Nov 2017, 11:07

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If a = c*10^b and a and b are integers, what is the value of b?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42249

Kudos [?]: 132595 [0], given: 12326

If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 02 Oct 2017, 23:57
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

40% (01:13) correct 60% (01:09) wrong based on 30 sessions

HideShow timer Statistics

If a = c*10^b and a and b are integers, what is the value of b?

(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.
(2) 1 < b < 4
[Reveal] Spoiler: OA

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 132595 [0], given: 12326

1 KUDOS received
Director
Director
avatar
P
Joined: 25 Feb 2013
Posts: 542

Kudos [?]: 246 [1], given: 33

Location: India
Schools: Mannheim"19 (S)
GPA: 3.82
GMAT ToolKit User Reviews Badge
If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 02:20
1
This post received
KUDOS
Bunuel wrote:
If a = c*10^b and a and b are integers, what is the value of b?

(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.
(2) 1 < b < 4


Statement 1: \(c=0.xyz\), where \(x,y,z\) are digits in tenths, hundredths, and thousandths places but nothing mentioned about \(a\) or \(b\). Hence \(insufficient\)

Statement 2: \(b\) can be \(2\) or \(3\). Hence insufficient

Combining 1 & 2. \(a = c*10^b\),

or \(a= 0.xyz*10^b\) we know that \(a\) is an integer, hence \(b=3\) because if \(b=2\) then \(a=xy.z\) which is not an integer. Hence sufficient

Option C

Last edited by niks18 on 15 Oct 2017, 02:00, edited 2 times in total.

Kudos [?]: 246 [1], given: 33

Senior Manager
Senior Manager
User avatar
G
Joined: 02 Jul 2017
Posts: 269

Kudos [?]: 79 [0], given: 65

Location: India
GMAT ToolKit User CAT Tests
If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 02:39
If \(a = c*10^b\)and a and b are integers, what is the value of b?

(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.
=> This tells us that c is a 3 digit decimal number => c = 0.pqr ( p,q,and r are single digit integers)

to make 'a' as an integer 'c' need to be multiplied by 1000 => minimum value of a => \(a = c*10^3\)
Here as we don't know value of a => b can take any value greater or equal to 3 => \(b\geq{3}\)
Insufficient

(2) 1 < b < 4
as b is an integer => b = 2 or 3
Insufficient

1+2

=>by statement 1=> \(b\geq{3}\)
by statement 2 => b = 2 or 3
=> b=3

Answer: C

Kudos [?]: 79 [0], given: 65

Manager
Manager
avatar
B
Joined: 14 Sep 2016
Posts: 148

Kudos [?]: 5 [0], given: 36

Re: If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 07:01
(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.

How come you can deduce that "C" is a decimal digit ?

Kudos [?]: 5 [0], given: 36

Director
Director
avatar
P
Joined: 25 Feb 2013
Posts: 542

Kudos [?]: 246 [0], given: 33

Location: India
Schools: Mannheim"19 (S)
GPA: 3.82
GMAT ToolKit User Reviews Badge
Re: If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 07:12
kunalsinghNS wrote:
(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.

How come you can deduce that "C" is a decimal digit ?


Hi kunalsinghNS

it is mentioned in the statement that ONLY tenths, hundredths, and thousandths places have non zero digits
So \(c=0.234\) or \(c=10.897\). In either case if you multiply \(c\) by \(10^3\), then it will become an integer

Kudos [?]: 246 [0], given: 33

Senior Manager
Senior Manager
User avatar
G
Joined: 02 Jul 2017
Posts: 269

Kudos [?]: 79 [0], given: 65

Location: India
GMAT ToolKit User CAT Tests
If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 08:54
kunalsinghNS wrote:
(1) c has nonzero digits in only the tenths, hundredths, and thousandths places.

How come you can deduce that "C" is a decimal digit ?


Please refer attached figure and below mentioned line, it might help.

c has nonzero digits in only the tenths, hundredths, and thousandths places.
Attachments

Number.jpg
Number.jpg [ 16.72 KiB | Viewed 393 times ]

Kudos [?]: 79 [0], given: 65

Manager
Manager
avatar
B
Joined: 14 Sep 2016
Posts: 148

Kudos [?]: 5 [0], given: 36

Re: If a = c*10^b and a and b are integers, what is the value of b? [#permalink]

Show Tags

New post 03 Oct 2017, 19:53
Thank you for the explanation niks18 and Nikkb

Kudos [?]: 5 [0], given: 36

Re: If a = c*10^b and a and b are integers, what is the value of b?   [#permalink] 03 Oct 2017, 19:53
Display posts from previous: Sort by

If a = c*10^b and a and b are integers, what is the value of b?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.